The sealing of electrical components so as to prevent contamination and deterioration from exposure to the atmosphere is important for many applications and in some instances is critical. The sealing of electrical components is particularly important in the field of semiconductor packaging. The microcircuitry of the semiconductor chip may readily undergo failure since the circuitry on such miniature components is often on the order of microns, such circuit dimensions being readily subject to short or open failure upon exposure to the environment. In addition to failure of the connective circuitry, atmospheric contamination of the semiconductor material itself may drastically effect its electrical response.
Some components are often sealed and protected from the atmosphere by fusing a glass layer thereover. Alternatively, a metal cap may be used to seal the electrical components by soldering the cap over the substrate on which the semiconductor chip has been mounted.
Such prior art methods of sealing electrical components to protect them from the environment requires subjecting the electrical device to considerable thermal stress, since the solder or glass must be heated to its melting temperature. For many electrical applications such as where expensive, high density semiconductor chips are utilized, a hermetic seal is required. Such a seal allows no detectable leakage when tested with a helium mass spectrometer leak tester of sensitivity 1 .times. 10.sup.-8 ssc/sec. in accordance with MIL-Standard 883. Prior art methods of forming such seals have generally involved delicate and expensive sealing operations such as precious metal soldering or the fusion of a sealing glass to itself and to metallic leads.
Also, once a component is protected from the atmosphere by such prior art methods, it cannot be easily replaced. Rather, if changes in circuitry are required, the fabrication of an entirely new package is often required. It is thus an object of this invention to provide a method of sealing electrical components which is more reliable and less costly than the methods of the prior art.
It is another object of this invention to provide a method of sealing electrical components which will not subject the electrical component or substrate to excessively high temperatures, thereby permitting the use of a wider range of component materials and substrates, including plastics.
It is still another object of this invention to provide a sealing means which may be readily removed so that access to the sealed electrical component may be had if repair or replacement of the component is desired.